In a conventional mobile network, a Base Station Controller (BSC) is only connected to one Mobile Switch Center (MSC), while the MSC may be connected to a plurality of BSCs. An interface between the MSC and the BSC is an A interface, and the protocol of the A interface is borne on the Signaling Connection Control Part (SCCP). Generally, when a user initiates a certain service, for example, a call, an SCCP connection between the MSC and the BSC may be established for the service. The establishment of the SCCP connection may be initiated by the BSC, or may also be initiated by the MSC. After the MSC Pool networking is introduced, the BSC may be connected to a plurality of MSCs through a Serving Node Selection Function (SNSF). Specifically, the BSC may be connected to different SNSFs through different links, and the SNSF presents a unique MSC identifier for the BSC, and therefore, the BSC is still merely connected to one MSC. A service request transmitted by the BSC is forwarded through the SNSF, and is distributed to different MSCs for processing. In this way, when a failure occurs on a certain MSC in the MSC Pool, the service may still be forwarded to other MSCs for processing, thereby improving the reliability of the network.
Before the MSC Pool networking, the MSC transmits a message to the BSC through a signaling point of the BSC, and then the BSC transmits the message to the MSC through a signaling point of the MSC. After the MSC Pool networking, the message transmitted between the MSC and the BSC is forwarded to the opposite end through the SNSF therebetween. In the service interaction between the BSC and the MSC, since the interaction message is lost, a phenomenon that the SCCP connection resource at one side is released while the SCCP connection resource at the other side is still occupied may occur. In order to avoid the deadlock of the single side connection resource, the following two solutions are provided in the SCCP.
One solution is as follows. In the MSC Pool networking, when a certain MSC crashes due to a failure, after the MSC is restarted as the failure is removed, since a service connection relation established on the MSC is lost, the MSC is required to transmit a global reset message to the BSC connected thereto. After the BSC receives the reset message, the BSC starts a timer, releases all the service connections established thereon, and transmits a Reset Acknowledge message to the MSC to indicate that the release of the connection resources is completed after the timer expires (the timer is disposed to ensure that all the related resources on the BSC are released). Before the BSC releases all the resources, in order to avoid abnormal SCCP connection between the MSC and the BSC, the BSC does not allow new services to be connected.
The other solution is as follows. The SCCP defines a connection check and release mechanism, that is, an Inactivity Test (IT) message is used to perform steady state detection. Specifically, after the failure of the MSC is removed, the MSC does not transmit the global reset message to the BSC, and all the corresponding original SCCP connections of the MSC on the BSC after the failure is removed need to be released through the IT detection.
In the implementation of the present invention, the inventor finds that the prior art at least has the following problems.
As for the first solution, in the MSC Pool networking, after the failure of a certain MSC is removed, the global reset message is transmitted to all the BSCs, and the BSCs release all the calls after receiving the global reset message. In this way, the services distributed to other normal MSCs are also abnormally released, that is, all the calls of the whole MSC Pool networking are abnormally released after the failure of the single MSC is removed.
As for the second solution, since the duration of the T(iar) timer of the SCCP connection is relatively long (the T(iar) timer is set at a local end, and the timer is restarted every time the message from the opposite end is received, and if the T(iar) timer expires, it is considered that the deadlock of the local connection resources occurs, and then the local connection resources are released), before the T(iar) timer of the SCCP connection at the BSC side expires, a connection reference number allocated by the MSC corresponding to the SCCP connection recorded on the BSC is released on the MSC. Therefore, when a new service is distributed to the MSC, the SCCP connection allocated by the MSC to the new service may still be not released on the BSC. In this way, the connection reference number newly allocated by the MSC practically exists in a mapping record of the BSC, and a phenomenon where two records on the BSC correspond to one connection reference number allocated by the MSC might occur. For example, a user A initiates a call, the connection reference number allocated on the MSC is “1”; after the failure of the MSC is removed, a user B initiates a call, and the MSC allocates the connection reference number “1” to the user B. The BSC transmits the subsequent service message of the user A to the MSC through a DT1 message, where the DT1 message merely includes a destination local reference number (allocated by the MSC), and the MSC may treat the service message of the user A as the service message of the user B for processing according to the destination local reference number in the DT1 message. When a large number of SCCP connections on the BSC are not released in the period of the MSC failure, after the failure is removed, the processing of the new services is conflicting and chaotic due to inconsistency of the connection states at two sides of the MSC and the BSC.
In conclusion, in the prior art, after the failure of the MSC in the MSC Pool networking is removed, and the reset message is transmitted, the normal services of other MSCs may be affected accordingly, and the new services may be affected due to the inconsistency of the connection states at the two sides of the MSC and the BSC, so the Quality of Service (QoS) of the services is lowered.